Matt, yes you do need to read the manual but I'll try and summarize it a little bit for you...
4High open is what the truck runs in all the time.
4High lock is a mid speed range where 50% torque is sent to the front diff and %50 power is sent to the rear diff and all wheels are locked in spinning at one speed.
4Low Lock is for severe off roading and if you have a auto trans it should be in low 1. This gives you the most torque to crawl over obstacles. It's a very slow speed given to you from the transfer case. You shouldn't go over 10-15 mph in this setting.
For instance, if you were to run in some sand dunes or something like that you would run in 4 high lock and drop the shifter into 3rd gear and have at it!
If you were climbing some rocks or up a very steep hill, drop it into 4 low lock an put the shifter in low 1. This way you will crawl right up the hill or rocks.
Not knowing what this hill looked like that you went up it's hard to give you advise as to what 4 wheel drive option to use. From what you said it doesnt sound to hard.
But yes, time to get out the owners manual and read about your 4 wheel drive options. You certainly don't want to be embarrased if you get stuck because you didn't have the truck in the correct 4 wheel drive setting.
